Fix the restconf deletion of leaf list items.

Leaf list items were not being detected properly and hence not being
set to NULL when the flag SCF_F_SET_NULL was set.

schema.c

@@ -3890,6 +3890,19 @@ _sch_traverse_nodes (sch_node * schema, GNode * parent, int flags, int depth, in
                 name = NULL;
             }
         }
+        else if (!child && flags & SCH_F_SET_NULL && g_strcmp0 (name, "*") == 0)
+        {
+            xmlNode *xml = (xmlNode *) schema;
+
+            if (sch_is_leaf_list (xml->parent))
+            {
+                for (GNode *child = parent->children; child; child = child->next)
+                {
+                    free (child->children->data);
+                    child->children->data = g_strdup ("");
+                }
+            }
+        }
         else if (child && flags & SCH_F_SET_NULL)
         {
             if (!(flags & SCH_F_FILTER_RDEPTH) || (depth >= rdepth))